1. Field of the Invention
This invention relates to an improved endless power transmission belt having a toothed compression section and to a method of making the same.
2. Prior Art Statement
It is known to provide an endless power transmission belt having a toothed compression section wherein the belt is formed substantially of polymeric materials and comprises a tension section, a compression section, and a load-carrying section disposed between the tension section and the compression section, the compression section having an outer layer and an inner layer joined to the outer layer and defining an interface therewith that is substantially uniformly spaced from the load-carrying section by the outer layer throughout substantially the entire width and length of the belt and with the compression section having an inner surface in the form of alternating transverse teeth and grooves with the grooves respectively defining the roots of the teeth.
For example, see the following United States patent:
(1) U.S. Pat. No. 3,995,507--White et al
It appears that the endless power transmission belt of item (1) above has the roots of the teeth extending to the outer layer of the compression section thereof.
It is also known to form the inner layer of the toothed compression section of an endless power transmission belt of a softer compound than the outer layer thereof to tend to prevent cracking in the toothed area of the belt.
For example, see the following copending patent application:
(2) U.S. Ser. No. 232,326, filed Feb. 6, 1981--Miranti, Jr.
It appears that the interface between the inner and outer layers in the toothed compression section in the belt of item (2) above is substantially the same as the contour of the alternating teeth and grooves of the inner surface of the compression section of the belt.
It is also known to provide a soft rubber layer between the inner and outer layers of the compression section of an endless power transmission belt that has a toothed compression section.
For example, see the following U.S. Patent:
(3) U.S. Pat. No. 3,473,989--Richmond.
It appears that the endless transmission belt of item (3) above has the roots of the teeth thereof extending to an intermediate soft rubber layer disposed between the inner layer and outer layer of the compression section thereof, the soft intermediate layer tending to prevent cracks in the toothed area from reaching the outer layer of the compression section thereof.
It is also known to provide a fabric layer between the inner layer and outer layer of the toothed compression section of an endless power transmission belt in order to tend to prevent cracks in the toothed area from reaching the outer layer of the compression section.
For example, see the following U.S. Patent:
(4) U.S. Pat. No. 4,188,832--Henderson.
It is also known to provide two or more layers in the non-toothed compression section of an endless transmission belt wherein the inner layer is softer than the outer layer of the compression section.
For example, see the following two United States Patents:
(5) U.S. Pat. No. 2,417,512--Nassimbene.
(6) U.S. Pat. No. 3,164,026--Terhune.